U.S. patent application number 10/449431 was filed with the patent office on 2004-12-02 for fluid-sealed anti-vibration device.
This patent application is currently assigned to Toyo Tire & Rubber Co., Ltd.. Invention is credited to Hamanaka, Takeshi, Hatakeyama, Shingo, Itoh, Masaaki, Takashima, Yukio.
Application Number | 20040239021 10/449431 |
Document ID | / |
Family ID | 33451784 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040239021 |
Kind Code |
A1 |
Itoh, Masaaki ; et
al. |
December 2, 2004 |
Fluid-sealed anti-vibration device
Abstract
In an anti-vibration device having a partition member dividing a
fluid-sealed chamber into upside and downside, aimed at enhancing
the anti-vibration performance by preventing unwanted leak of the
fluid through through-holes of the partition member. To that end,
the partition member is constructed of an elastic membrane
partitioning the fluid-sealed chamber, and a pair of grids limiting
displacements of the elastic membrane; and the elastic membrane is
provided at its either surface with projecting streaks integral
therewith, the projecting streaks surrounding through-holes,
defined by the grids, over their whole peripheries and abutting on
the grids, thereby regulating the flow of fluid among adjacent
through-holes.
Inventors: |
Itoh, Masaaki; (Nishiku,
JP) ; Hatakeyama, Shingo; (Osaka, JP) ;
Takashima, Yukio; (Osaka, JP) ; Hamanaka,
Takeshi; (Ebina-shi, JP) |
Correspondence
Address: |
JORDAN AND HAMBURG LLP
122 EAST 42ND STREET
SUITE 4000
NEW YORK
NY
10168
US
|
Assignee: |
Toyo Tire & Rubber Co.,
Ltd.
Osaka
JP
221-0023
Nissan Motor Co., Ltd.
Yokohama-shi
JP
|
Family ID: |
33451784 |
Appl. No.: |
10/449431 |
Filed: |
May 29, 2003 |
Current U.S.
Class: |
267/140.13 |
Current CPC
Class: |
F16F 13/106
20130101 |
Class at
Publication: |
267/140.13 |
International
Class: |
F16F 009/00 |
Claims
1. A fluid-sealed anti-vibration device, comprising: a first
attachment member; a second attachment member; a vibration
insulating base, made of a rubber material, connectingly interposed
between the first and second attachment members; a diaphragm, on
the second attachment member, opposite to the vibration-insulating
base; a fluid-sealed chamber, disposed between the
vibration-insulating base and the diaphragm; a partition member,
comprising an elastic membrane, having opposite surfaces, for
partitioning the fluid sealed chamber into a first chamber at a
vibration-insulating base side, and a second chamber at a diaphragm
side; an orifice channel in communication with the first chamber
and the second chamber; a pair of grids for limiting displacement
of the elastic membrane; and a plurality of projections, arranged
in a framework structure, between either surface of the elastic
membrane and respective surfaces of the grids facing either
surface, said projections surrounding through-holes delimited by
the grids over their entire peripheries, and regulating transfer of
fluid among adjacent through-holes.
2. The fluid-sealed anti-vibration device as set forth in claim 1,
wherein the projections are provided integrally with one of: either
surface of the elastic membrane, and respective surfaces of the
grids facing either surface.
3-8. Canceled
9. A fluid-sealed anti-vibration device comprising: a first
attachment member; a second attachment member; a
vibration-insulating base, made of a rubber material connecting
interposed between the first and second attachment members; a
diaphragm, on the second attachment member opposite to the
vibration-insulating base; a fluid-sealed chamber, disposed between
the vibration-insulating base and the diaphragm; a partition
member, comprising an elastic membrane, for partitioning the
fluid-sealed chamber into a first chamber at a vibration-insulating
base side, and a second chamber at a diaphragm side; a first member
disposed at the vibration insulating base side relative to the
elastic membrane; and a second member disposed at the diaphragm
side relative to the elastic membrane and crimped at its peripheral
area to the second attachment member to urge a peripheral portion
of the first member to a peripheral portion of the
vibration-insulating base at the fluid-sealed chamber side; an
orifice channel in communication with the first chamber and the
second chamber; such that one of the first member and the second
member is provided with a depressed part for housing therein the
elastic membrane, and the other member is provided with a flat
planar part abutting on an edge surface of an opening of the
depressed part so as to close the opening of the depressed part,
thus forming a clearance limiting displacement of the elastic
membrane between the first member and the second member.
10. The fluid-sealed anti-vibration device as set forth in claim 9,
wherein the first member and the second member are made of diferent
materials.
11. The fluid-sealed anti-vibration device as set forth in claim
10, wherein the first member is formed with the depressed part and
is made of resin; and the second member is formed with the flat
planar part and is made of metal.
12. The fluid-sealed anti-vibration device as set forth in claim 9,
wherein the first member is provided at its outer periphery with a
vertical wall for shutting off flow through the orifice channel in
a circumferential direction; the vertical wall having at an end of
the wall an elongated portion inserted in a hole in the second
member, thereby enabling the positioning of the first member and
the second member in a direction of revolution.
13. The fluid-sealed anti-vibration device as set forth in claim
12, wherein the elongated portion of the vertical wall is formed
with a hook that in engages an opening edge of the hole.
14. The fluid-sealed anti-vibration device as set forth in claim 9,
wherein: the first member includes a first grid opposite to one
surface of the elastic membrane, limiting displacement of the
elastic membrane; the second member includes a second grid opposite
to the other surface of the elastic membrane, limiting displacement
of the elastic membrane; and a plurality of projections, arranged a
framework structure, are provided between either surface of the
elastic membrane and surfaces of the first and second grids
opposing respective surfaces of the elastic membrane, such that the
projections surround through-holes defined by the grids over an
entire periphery of the grids, and regulate transfer of fluid among
adjacent through-holes.
15. Canceled
16. The fluid-sealed anti-vibration device as set forth in claim 1,
wherein: the partition member comprises the elastic membrane
partitioning the first chamber and the second chamber; a first
member is disposed at a vibration-insulating base side relative to
the elastic membrane; and a second member is disposed at a
diaphragm side relative to the elastic membrane, and is crimped
around a periphery thereof to the second attachment member, to urge
a peripheral portion of the first member to a peripheral portion of
the vibration-insulating base at a fluid-sealed chamber side; such
that one of the first member and the second member is provided with
a depressed part for housing therein the elastic membrane and the
other member is provided with a flat planar part abutting an edge
surface of an opening of the depressed part, so as to close the
opening of the depressed part, thus forming a clearance-limiting
displacement of the elastic membrane between the first member and
the second member.
17. The fluid-sealed anti-vibration device as set forth in claim
16, wherein the first member and the second member are made of
different materials.
18. The fluid-sealed anti-vibration device as set forth in claim
17, wherein the first member is formed with the depressed part and
is made of resin; and the second member is formed with the flat
planar part and is made of metal.
19. The fluid-sealed anti-vibration device as set forth in claim
16, wherein the first member is provided at its outer periphery
with a vertical wall for shutting off flow through the orifice
channel in a circumferential direction; the vertical wall having at
an end thereof an elongated portion inserted in a hole in the
second member, for enabling the positioning of the first member and
the second member in a direction of revolution.
20. The fluid-sealed anti-vibration device as set forth in claim
19, wherein the elongated portion of the vertical wall is formed
with a hook that engages an opening edge of the hole.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a fluid-sealed anti-vibration
device principally for use in an automotive engine or any other
vibratory body in a vibration-proof manner.
[0003] 2. Description of Related Art
[0004] A typical fluid-sealed anti-vibration device is constructed
so that a first fitting to be mounted on a vibration-generator side
such as an engine and a second fitting of a cylindrical form to be
mounted and secured to a support side such as a vehicle frame, etc.
are connected through a vibration-insulating base made of a rubber
material, a diaphragm is disposed to oppose the
vibration-insulating base at a lower side of the second fitting, an
internal room between the vibration-insulating base and the
diaphragm is made into a fluid-sealed chamber, which is in turn
divided by a partition member into two chambers at the
vibration-insulating base side and at the diaphragm side, both
chambers being put into communication with each other through an
orifice, whereby a vibration-damping function is performed owing to
a liquid fluidization effect between both liquid chambers through
the orifice and a vibration-insulating effect of the
vibration-insulating base.
[0005] Of fluid-sealed anti-vibration devices of this type, such a
device is known in the art that has a partition member constructed
of an elastic membrane, as a valve member, reciprocating to
displace and a pair of upper and lower grids limiting the movement
of the elastic membrane. With the anti-vibration device having the
elastic membrane like this, under low frequency and large amplitude
vibrations such as a vibration ascribed to irregularities on the
road surface when the vehicle is traveling, the fluid flows through
the orifice to fluidize between the two chambers, as a result of
which the device serves to exhibit a vibration-damping function. On
the other hand, under high frequency and slight amplitude
vibrations such as a vibration ascribed to revolution number of the
engine, the above-mentioned orifice does not work, but the elastic
membrane reciprocates to deform thereby exhibiting a
vibration-damping function.
[0006] FR Patent Publication No. 2674590 A discloses a one wherein
a partition member partitioning an upper and a lower liquid
chambers is made up of a pair of upper and lower grids and an
elastic membrane held between the grids. According to the patent
publication, the elastic membrane is provided so that its central
part may be sandwiched and held between the upper and lower grids
and its peripheral portion may float, the elastic membrane being
provided at least one surface thereof with bosses or protuberances
opposing the grids in order to prevent the generation of impinging
sound of the membrane on the grids and unwanted noise. These bosses
are arranged on the surface of the elastic membrane so as to be
juxtaposed equally in a ring fashion and have the function that
they are pressed stepwise toward the grid and then elastically
relax when the elastic membrane works.
[0007] U.S. Pat. No. 5,443,245 discloses another one, wherein the
partition member comparting the upper and lower chambers is
constructed of a pair of upper and lower orifice members having a
grid at each central part and forming an orifice channel at each
peripheral part, and an elastic membrane held between both orifice
members. It further discloses the technology that with a view to
preventing the generation of impinging sound of the elastic
membrane on the grids and unwanted noise, the grid, not the elastic
membrane, is provided with angularly adjacent, but non-repetitive
non-uniform ribs wholly around the axis line.
[0008] The bosses or the ribs in the prior art technology mentioned
above are thus provided to diminish the shock sound when the
elastic membrane is displaced up and down to impinge on the grids,
but not to limit the transfer of the sealed liquid in a
circumferential direction and a radial direction among
through-holes formed by the grids. In the conventional devices,
therefore, transfer or leak of the sealed liquid among contiguous
through-holes of the grids occurs under low frequency and large
amplitude vibrations, with the result that it would be difficult to
exhibit higher performance.
[0009] Again the conventional vibration-proof devices above can
diminish the impinging sound or noise by means of the bosses or
ribs in a sense, but the peripheral part of the elastic membrane is
not restrained at all, which causes the peripheral part of the
elastic membrane to flap due to a rapid change in hydraulic
pressure. Hence it would be difficult to prevent necessarily
sufficiently the generation of impinging sound and noise. In
addition, these devices are inferior in assembling workability, as
well: For instance, in assembling the partition member, the
peripheral portion of the elastic membrane is liable to turn up; or
when the elastic membrane will be inserted between the grids, a
flat shape of the elastic membrane makes it difficult to
insert.
[0010] With the above-mentioned anti-vibration device disclosed in
U.S. Pat. No. 5,443,245, the orifice members of a same material are
fitted in the elastic membrane thus configuring the orifice flow
channel and a movable clearance of the elastic membrane. In that
case, the only way to enhance the fitting precision was either to
machine (cut) the fitting surface or to make a sacrifice of the
dimensional precision in movable clearance of the elastic membrane.
That is, the clearance dimension of the upper and lower orifice
members when assembled is set by setting respective dimensions of
them to be fitted and consequently, in particular where components
with a large fabrication tolerance are assembled together, it was
not easy to ensure the dimensional precision of the movable
clearance.
SUMMARY OF THE INVENTION
[0011] A primary object of this invention is to enhance
anti-vibration performance by preventing unwanted leak of the
sealed fluid among through-holes of the partition member.
[0012] Another object of this invention is to prevent the flapping
of the peripheral part of the elastic membrane of the partition
member and to enhance the assembling workability.
[0013] A further object of the invention is to enhance the
dimensional precision of the movable clearance for the elastic
membrane of the partition member.
[0014] A fluid-sealed anti-vibration device according to a first
embodiment of this invention comprises a first attachment member; a
second attachment member; a vibration-insulating base made of a
rubber material interposed between both attachment members to
connect them; a diaphragm attached to the second attachment member
to oppose the vibration-insulating base; a fluid-sealed chamber
provided between the vibration-insulating base and the diaphragm; a
partition member dividing the liquid-sealed chamber into a first
chamber at the vibration-insulating base side and a second chamber
at the diaphragm side; and an orifice channel putting the first
chamber and the second chamber into communication with each other,
wherein the partition member includes an elastic membrane
partitioning the first chamber and the second chamber, a pair of
grids limiting displacements of the elastic membrane, and
projecting streaks in the form of a framework structure provided
between either surface of the elastic membrane and one surface of
each of the grids opposing the either surface, the projecting
streaks surrounding respective through-holes defined by the grids
over whole peripheries of the through-holes and regulating the
transfer of fluid among contiguous through-holes of the grids.
[0015] By the provision of the aforesaid projecting streaks
surrounding whole peripheries of the through-holes of the grids
between the elastic membrane and the grids opposing it, the
projecting streaks serve to prevent leak of the fluid among
contiguous through-holes, in particular, under low frequency and
large amplitude vibrations. As a consequence, it is possible to
flex the elastic membrane to every through-hole, and a high loss
factor is attainable. Under high frequency and slight amplitude
vibrations, it may also be possible to construct so that the fluid
can flow beyond the projecting streaks. Then the fluid flowing
beyond the projecting streaks mollifies the hydraulic pressure
difference, exhibiting a low dynamic spring constant. According to
the first embodiment, it follows from the above that it is possible
to enhance the anti-vibration performance.
[0016] In the first embodiment stated above, the projecting streaks
can be formed integrally either with each surface of the elastic
membrane or with one surface of each of the grids vis-a-vis the
former. More particularly, the grids each consist of a plurality of
annular portions extending circumferentially and joint portions
radially extending to interconnect the plurality of annular
portions, thus constituting two or more through-hole rows, each
consisting of a plurality of through-holes circumferentially
juxtaposed. Here, in one embodiment, the joint portions of each
grid are arranged in different pitches between the inner periphery
side and outer periphery side of the grid; and the projecting
streaks are provided on the elastic membrane and consist of a
plurality of annular projecting pieces extending circumferentially
correspondingly to the annular portions of the grid and a plurality
of radial projecting pieces extending radially correspondingly to
the joint portions of the grid, the radial projecting pieces
extending in a nearly whole radial length of the elastic membrane
and in a radial manner at intervals of an equal angle. In that
case, some of the radial projecting pieces do not rest on the joint
portions of the grid. Nevertheless such projecting streaks out on
the grid hinder by no means the flexing behavior of the elastic
membrane to every through-hole. Therefore even such projecting
streaks that are equally arranged around an axis line of the
elastic membrane do not affect that function.
[0017] In the first embodiment above, in case where the projecting
streaks are provided integrally on the elastic membrane, the
positioning of the elastic membrane in its revolution direction may
be carried out by providing the elastic membrane with a positioning
lug (projection) while providing the grid with a positioning
recessed portion such that the lug can be fitted therein, and
fitting both together. By this means it is possible to rest the
radial projecting pieces provided on the elastic membrane securely
on the joint portions of the grid.
[0018] A fluid-sealed anti-vibration device with which a second
embodiment of this invention is concerned comprises a first
attachment member; a second attachment member; a
vibration-insulating base made of a rubber material interposed
between these attachment members to connect them; a diaphragm
opposing the vibration-insulating base and attached to the second
attachment member; a fluid-sealed chamber provided between the
vibration-insulating base and the diaphragm; a partition member
dividing the fluid-sealed chamber into a first chamber at the
vibration-insulating base side and a second chamber at the
diaphragm side; and an orifice putting the first chamber and the
second chamber into communication with each other, wherein the
partition member comprises an elastic membrane partitioning the
first chamber and the second chamber; a first member including a
first grid disposed to face the one surface of the elastic membrane
and limiting displacement of the elastic membrane and a first
vertical wall extending from a peripheral portion of the first grid
to surround an outer periphery of the elastic membrane; and a
second member including a second grid disposed to face the other
surface of the elastic membrane and limiting displacement of the
elastic membrane and a second vertical wall extending from a
peripheral portion of the second grid and disposed to face an inner
peripheral side of the first vertical wall; the elastic membrane
being provided with a vertical wall section that extends from a
peripheral portion of the elastic membrane and is inserted in a gap
between the first vertical wall and the second vertical wall.
[0019] In the second embodiment above, due to the vertical wall
section provided at the peripheral portion of the elastic membrane,
the peripheral portion of the elastic membrane is hindered from
flapping owing to a rapid change in hydraulic pressure. As a
consequence, it is possible to preclude the generation of impinging
sound of the elastic membrane on the grids and unwanted noise.
Further due to the vertical wall section of the elastic membrane,
identification of the elastic membrane between its surface side and
back side becomes easy, inserting operation of the elastic membrane
into the first member is facilitated, and besides, turning-up at
the peripheral portion of the elastic membrane can be avoided. Thus
the assembling workability of the partition member is enhanced.
[0020] It is preferred to apply the construction of the first
embodiment described above to this second embodiment. That is, in
the second embodiment it is preferred to provide projecting
streaks, in the form of a framework structure, between either
surface of the elastic membrane and each one surface of the first
and second grids opposing the former, the projecting streaks
surrounding respective through-holes defined by the grids around
whole peripheries thereof and regulating flow of the fluid among
adjacent through-holes of the grids.
[0021] A fluid-sealed anti-vibration device according to a third
embodiment comprises a first attachment member; a second attachment
member; a vibration-insulating base made of a rubber material
interposed between these attachment members to connect them; a
diaphragm opposing the vibration-insulating base and attached to
the second attachment member; a fluid-sealed chamber provided
between the vibration-insulating base and the diaphragm; a
partition member dividing the fluid-sealed chamber into a first
chamber at the vibration-insulating base side and a second chamber
at the diaphragm side; and an orifice channel putting the first
chamber and the second chamber into communication with each other,
wherein the partition member comprises an elastic membrane
partitioning the first chamber and the second chamber; a first
member disposed at the vibration-insulating base side relative to
the elastic membrane; and a second member disposed at the diaphragm
side relative to the elastic membrane and having a peripheral
portion crimped to the second attachment member thereby urging a
peripheral portion of the first member toward a peripheral portion
of the vibration-insulating base at the fluid-sealed chamber side,
one of the first member and the second member being provided with a
depressed part for receiving the elastic membrane and the other
being provided with a flat plane part abutting on an edge surface
of an opening of the depressed part so as to shut off the opening
of the depressed part, the first member and the second member
forming therebetween a clearance limiting displacements of the
elastic membrane.
[0022] In accordance with this third embodiment, in the partition
member forming an orifice channel at its outer periphery, the
dimension of the movable clearance for the elastic membrane is
defined depending upon the depth of the depressed part provided
either on the first member or on the second member. That is to say,
it is possible to set that dimension for regulating displacements
of the elastic membrane only at one side of either the first member
or the second member. As a consequence, it is possible to enhance
the dimensional precision of the movable clearance as compared to
the case where dimensional setting is performed by a combination of
the both. With the recent request for higher performance of
vehicles, wherein a high dimensional precision is also required for
the movable clearance of the elastic membrane, the third embodiment
can meet this request by such a simple combination at a low
cost.
[0023] In the third embodiment, the first member and the second
member can be made of dissimilar materials, wherein one member
smaller in fabrication tolerance is provided with the aforesaid
depressed part whereby it is possible to set the movable clearance
by only one member of a good precision. For example, the first
member may be provided with the depressed part and fashioned of a
resin whereas the second member may be provided with the flat plane
part and fashioned of a metal. Here as regards the second member to
be secured by crimping, it is fashioned of a metal such as a
pressed steel sheet or aluminum casting whereby it is possible to
ensure such a strength that withstands the crimping. On the other
hand, as regards the first member on which dimensional setting of
the movable clearance is made, it is fashioned of a resin having a
good dimensional precision, whereby it is possible to ensure a
dimensional precision of the movable clearance without applying a
cutting processing. Further a weight reduction can also be achieved
by use of the resin.
[0024] Preferably the third embodiment is constituted so that the
first member and the second member basically may not contact with
each other in other areas than the abutting area of the flat plane
part and the opening edge surface of the depressed part. However,
for the purpose of positioning both members in the revolution
direction, it doesn't matter that both are partly in contact in the
other areas. For example, in cases where the first member is
provided at its outer peripheral area with a vertical wall shutting
off the flow in the orifice channel in the circumferential
direction, it is possible to elongate a tip end of the vertical
wall and to insert the elongated or extension portion in a hole
apertured in the peripheral portion of the second member. Here,
when the extension portion is applied on the opening margin of the
hole, the positioning of the first member and the second member in
the revolution direction can be performed. Furthermore since the
vertical wall here is extended up to the second member side, the
extension portion can avoid unwanted leak of fluid from between the
tip end of the vertical wall and the second member. Otherwise the
extension portion of the vertical wall may be formed with a hook,
which is caught in the opening margin of the hole, whereby upon
fabrication the first member and the second member are prevented
from disengaging and revolving.
[0025] It is also possible to apply the construction of the first
embodiment stated above to the third embodiment. In that case, the
first member is disposed to face the one surface of the elastic
membrane and provided with the first grid limiting the displacement
of the elastic membrane; the second member is disposed to face the
other surface of the elastic membrane and provided with the second
grid limiting the displacement of the elastic membrane; between
both surfaces of the elastic membrane and respective surfaces of
the first grid and the second grid there are provided projecting
streaks, in the form of a framework structure, surrounding
through-holes defined by the grids over whole peripheries thereof
and regulating the transfer or flow of fluid among adjacent
through-holes of the grids.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a longitudinal sectional view of an anti-vibration
device pertaining to a first example of this invention;
[0027] FIG. 2 is a sectional view illustrating the same device in
an exploded state;
[0028] FIG. 3 is an enlarged view of FIG. 2 in the circumscribing
part X;
[0029] FIG. 4A is a perspective view of a lower member in that
example, FIG. 4B a perspective view of a rubber membrane, and FIG.
4C a plan view of a combination of the lower member and the rubber
membrane;
[0030] FIG. 5A is a plan view showing a combination of the lower
member and the rubber membrane according to a second example, and
FIG. 5B a sectional view taken along Y-Y line in FIG. 5A;
[0031] FIG. 6 is a longitudinal sectional view of an anti-vibration
device according to a third example;
[0032] FIG. 7 is an exploded sectional view of the device in FIG.
6;
[0033] FIG. 8 is a perspective sectional view of a rubber membrane
in the third example;
[0034] FIG. 9A is a perspective view of a lower member in that
example, FIG. 9B a perspective view of a rubber membrane, and FIG.
9C a plan view of a combination of the lower member and the rubber
membrane;
[0035] FIG. 10 is a longitudinal sectional view of an
anti-vibration device pertaining to a fourth example;
[0036] FIG. 11A is an exploded sectional view showing a partition
member in the fourth example, FIG. 11B a sectional view of the
partition member in an assembled state, and FIG. 11C an enlarged
view of FIG. 11B in the circumscribing part V;
[0037] FIG. 12A is a side elevation of an upper member in the
fourth example, FIG. 12B a side elevation of a partition member,
and FIG. 12C an enlarged view of FIG. 12B in the circumscribing
part W;
[0038] FIG. 13 is a sectional view of an anti-vibration device
according to a fifth example; and
[0039] FIG. 14A is a side elevation of a partition member in the
fifth example showing its exploded state, and FIG. 14B a side
elevation of the partition member in its assembled state.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] The anti-vibration device relating to examples of this
invention will be hereinafter described in more detail with
reference to the accompanying drawings.
FIRST EXAMPLE
[0041] FIGS. 1 to 4 indicate a first example of this invention. The
anti-vibration device in the first example comprises a first
attachment member 10 to be mounted on a vibration-generator side
such as engine, a second attachment member 12 made of metal having
a cylindrical drum body to be mounted and secured to a support side
such as a vehicle frame, etc., and a vibration-insulating base 14
made of rubber material interconnecting the both.
[0042] The second attachment member 12 is composed of a generally
cylindrical fitting 16 constituting the aforementioned cylindrical
drum body, and a bottom fitting 18 fastened to the fitting 16 at
its lower end portion 16a by crimping means, the bottom fitting 18
having a bolt 19 for mounting provided projectingly.
[0043] The vibration-insulating base 14 assumes a nearly truncated
cone shape in outline, and its topside is secured to the first
attachment member 10 by vulcanization molding means whereas its
lower and outer peripheral portion is secured to an upper end
portion of the second attachment portion 12 by vulcanization
molding means. In the illustrated example, the upper end portion
16b of the cylindrical fitting 16 is configured to flare in a taper
form by upsetting, and the lower outer periphery of the
vibration-insulating base 14 is bonded to the upper end portion 16b
by vulcanization. On an inner wall surface of the second attachment
member 12 there is provided a thin film rubber portion 14a extended
from the vibration-insulating base 14.
[0044] At a lower side of the second attachment member 12, a
diaphragm 22 made of a rubber membrane is fitted so as to oppose
the vibration-insulating base 14. The diaphragm 22 is provided at
its outer peripheral area with a ring-like reinforcing fitting 24,
which is crimped and secured to a crimped area of the cylindrical
fitting 16 and the bottom fitting 18, whereby the diaphragm 22 is
attached to the second attachment member 12.
[0045] The second attachment member 12 internally forms a
fluid-sealed chamber 26 enclosed between the diaphragm 22 and the
vibration-insulating base 14. To an inner periphery of the second
attachment member 12 at the fluid-sealed chamber 26 side, a
disc-form partition member 30 having an orifice channel 28 is
fitted liquid-tightly. The fluid-sealed chamber 26 is divided
through the partition member 30 into a first chamber 26a at the
vibration-insulating base side and a second chamber 26b at the
diaphragm side, both chambers 26a, 26b being put into communication
with each other via the orifice channel 28.
[0046] The partition member 30 is constructed of a disk-like rubber
membrane 32 as a valve member partitioning the first chamber 26a
and the second chamber 26b, an upper member 36 disposed at the
vibration-insulating base 14 side relative to the rubber membrane
32 and having a groove 34 constituting the orifice channel 28, and
a lower member 38 disposed at the diaphragm side relative to the
rubber membrane 32 and urging an outer peripheral part of the upper
member 36 to the vibration-insulating base 14 side.
[0047] The upper member 36 is of a molding body made of metal or
resin and formed on its outer peripheral surface by the groove 34
extending circumferentially in a vertically two-cycle manner. A
space enclosed by this groove 34 and the thin film portion 14a of
the vibration-insulating base 14 is made into the orifice channel
28.
[0048] The lower member 38 is of a press molding body from a metal
sheet and has a central disk-shaped shelf part 38a protruding
upwardly. The lower member 38 is fitted to the second attachment
member 12, with its outer peripheral portion 38b crimped and
secured to the crimped area of the cylindrical fitting 16 and the
bottom fitting 18.
[0049] The upper member 36 and the lower member 38 are defined with
openings 37, 39 for bringing the orifice channel 28 into
communication with the first chamber 26a and the second chamber
26b, respectively.
[0050] The upper member 36 and the lower member 38 are formed at
their central areas by grids 40, 42, respectively, of a circular
form in outline limiting displacements of the rubber membrane 32 in
the vertical direction. The rubber membrane 32 is disposed within a
gap (a space for housing) 44 formed between the grid 40 of the
upper member 36 facing the first chamber 26a and the grid 42 of the
lower member 38 facing the second chamber 26b to the extent that
its displacement is restricted between both grids 40, 42. The
dimension or height of the gap 44 is set to be somewhat larger than
the thickness of the rubber membrane 32, whereby making the rubber
membrane 32 possible to displace and move up and down.
[0051] Both grids 40, 42 have one grid configuration. More
particularly, the grid 42 formed on the central shelf part 38a of
the lower member 38, as illustrated in FIGS. 4A and 4C, comprises
three concentric annular portions 42a extending circumferentially
and joint portions 42b extending radially to interconnect adjacent
two annular portions. The joint portions 42b are arranged in
different pitches between the inner periphery side and the outer
periphery side of the grid 42. In the illustrated example, four
joint portions 42b at the inner periphery side are arranged at
intervals of 90 degrees and eight joint portions 42b at the outer
periphery side are arranged at intervals of 45 degrees. Besides the
inner and outer joint portions 42b are arranged out of phase by
22.5 degrees so that both may not be in phase (both are not in
line). By this arrangement of the grid 42, two through-hole rows
are provided at the inner periphery side and the outer periphery
side of the grid, in each of which a plurality of elongate
through-holes 46 are juxtaposed circumferentially. Here, four
through-holes 46 at the inner periphery side and eight
through-holes 46 at the outer periphery side can be provided by
varying the pitch of the joint portions 42b as stated above. The
number of the through-holes 46 is made smaller at the inner
periphery side in this way, which enables it to ensure the opening
area of each through-hole 46 at the inner periphery side as large
as that at the outer periphery side. The grid 40 of the upper
member 36 also has the same configuration as that of the grid 42 of
the lower member 38. The upper member 36 is provided with
through-holes 45 in the same configuration and arrangement as that
of the through-holes 46 of the lower member 38, accordingly. These
upper member 36 and lower members 38 thus constructed are assembled
so that respective through-holes 45, 46 may be arranged in register
with one another.
[0052] The rubber membrane 32 is formed, on either surface thereof,
integrally with projecting streaks 48 that abut on each of surfaces
of the grids 40, 42 facing either surface of the rubber membrane to
surround respective through-holes 45, 46 over whole outer
peripheries thereof. As shown in FIG. 3, the projecting streaks 48
are provided in the same shape and structure on both upper and
lower surfaces of the rubber membrane 32. More particularly, the
projecting streaks 48 include, in the illustrated example of FIG.
4B, three concentric annular projecting pieces 48a extending
circumferentially correspondingly to the annular portions 42a of
the grid 42 and radial projecting pieces 48b extending radially
correspondingly to the joint portions 42b of the grid 42. The
radial projecting pieces 48b extend from a center of the rubber
membrane 32 over a whole radial length thereof. Further the radial
projecting pieces 48b are provided at intervals of 22.5 degree so
as to rest on all of the joint portions 42b of the grid 42 and to
extend radially at an equal angle.
[0053] According to the anti-vibration device thus constructed in
the first example, under low frequency and large amplitude (e.g.,
.+-.0.3 mm or more) vibrations the fluid flows through the orifice
channel 28 between two chambers 26a, 26b thereby exhibiting a
vibration-damping function. Due to the projecting streaks 48 formed
on the rubber membrane 32 serving to abut on bearing surfaces of
the grid 40, 42 the projecting steaks oppose, leaking of the fluid
among circumferentially or radially adjacent through-holes 45, 46
is prevented. Consequently it is possible to flex the rubber
membrane 32 at every one of the through-holes 45, 46, as a result
of which a high loss factor is obtainable. On the other hand, under
high frequency and slight amplitude (e.g., .+-.0.1 mm or less)
vibrations, the orifice channel 28 does not work, but a hydraulic
difference between the first chamber 26a and the second chamber 26b
is mollified by the fluid flowing beyond the projecting streaks 48
thereby to exhibit a low dynamic spring constant. To summarize, the
anti-vibration device according to the first example therefore can
achieve a high loss factor and a low dynamic spring constant while
eliminating the amplitude dependency, so that it is possible to
exhibit enough performance at different amplitudes.
[0054] As an aside, of the radial projecting pieces 48b arranged
equally about the axis line, some don't rest on the joint portions
of the grids 40, 42 owing to the arrangement way of the grids 40,
42 wherein the arrangement pitch of the joint portions is varied
between the inner periphery side and the outer periphery side. Even
such projecting streaks 48 that are out on the grids 40, 42,
however, never obstruct the flexing behavior of the rubber membrane
32 to every one of the through-holes 45, 46, and accordingly, never
impair the above-mentioned performance.
[0055] In this example, the embodiment wherein the projecting
streaks 48 are integrally formed on the rubber membrane 32 has been
so far described. Alternatively, the projecting streaks 48 may also
be formed integrally with the grids 40, 42. In that case, the
projecting streaks 48 formed on the grids 40, 42 serve to abut on
the rubber membrane 32, whereby leak of fluid among adjacent
through-holes 45, 46 is prevented.
SECOND EXAMPLE
[0056] The second example is, as shown in FIGS. 5A and 5B, such an
example that a positioning construction of the rubber membrane 32
in the revolution direction is added to the first example above.
That is, in this second example, the rubber membrane 32 is provided
with an ellipsoidal lug (projection) 50 for positioning that
project at the lower member 38 side. The lug 50 is situated in the
center of the rubber membrane 32. The lower member 38 is provided,
in the center of the central shelf part 38a, with a recess 52 for
positioning and receiving the lug 50 therein. The recess 52 is of a
complementary elongate hole conforming to the contoured form of the
lug 50.
[0057] According to this second example, in assembling the rubber
membrane 32 onto the lower member 38, the rubber membrane 32 is
rested on the grid 42 of the lower member 38 while the lug 50 of
the rubber membrane 38 is fitted in the recess 52 of the lower
member, whereby it is possible to ride securely the radial
projecting pieces 48b formed on the rubber membrane 32 on the joint
portions 42b of the grid 42.
[0058] The shapes of the lug 50 and the recess 52 are not limited
to the ellipsoidal shape as mentioned above if only positioning of
both in the revolution direction is possible, but various shapes
such as polygonal shape can be adopted. Otherwise the positioning
may also be effected by providing and fitting two sets of
positioning lugs and recesses.
THIRD EXAMPLE
[0059] FIGS. 6 to 9 indicate a third example of this invention. The
third example is similar to the first example except for the
construction of the partition member comparting the fluid-sealed
chamber 26. The similar elements designated by like reference
numerals in the first example have the same construction, and their
detailed explanation will be hereinafter omitted unless otherwise
stated.
[0060] In the third example, the partition member 100 comparting
the fluid-sealed chamber 26 is made up of a disk-like rubber
membrane 102 as a valve member partitioning the first chamber 26a
and the second chamber 26b, an upper member (a first member) 106
having a groove 104 for forming the orifice channel 28 at its outer
periphery, and a lower member (second member) 108 pressing the
outer peripheral portion of the upper member 106 toward the
vibration-insulating base 14 side.
[0061] The upper member 106 is fashioned of a molding body made of
metal or resin, and includes a grid (the first grid) 110 disposed
to oppose the top surface of the rubber membrane 102, and a
vertical wall (the first vertical wall) 112 extended from the
peripheral portion thereof to surround the outer periphery of the
rubber membrane 102. More particularly, the upper member 106
includes a cylindrical vertical wall 112 and the circular grid 110
spanning the interior of the vertical wall in a manner dividing it
vertically in the axially central area. On the outer peripheral
surface of the vertical wall 112 the groove 104 is formed to extend
circumferentially and over vertically two cycles.
[0062] The lower member 108 is of a press molding body of a metal
sheet, and includes a grid (second grid) 114 disposed to oppose the
lower surface of the rubber membrane 102, and a vertical wall
(second vertical wall) 116 disposed to oppose the inner periphery
side of the vertical wall 112 of the upper member 106. More
specifically, the lower member 108 is made up of a grid 114 having
a central shelf part of a circular form projecting upwardly, a
cylindrical vertical wall 116 extending downwardly from the
periphery of the grid 114, and an outer peripheral portion 118
extending from the lower end of the vertical wall 116 radially
outwardly. The lower member 108 is attached to the second member
12, with the outer peripheral portion 118 crimped and secured to
the crimped area of the cylindrical fitting 16 and the bottom
fitting 18.
[0063] The rubber membrane 102 is disposed in a gap 120 defined
between the grid 110 of the upper member 106 and the grid 114 of
the lower member 108, and its vertical displacements are limited
between both grids 110, 114. The height of the gap 120 is set to be
somewhat greater than the thickness of the rubber membrane 102
thereby enabling the rubber membrane 102 to displace up and
down.
[0064] The rubber membrane 102 is, as illustrated in FIG. 8,
configured in a sack shape, with its outer peripheral end bent
downwardly. That is, the rubber membrane 102 comprises a disk-like
main body 122 and a vertical wall section 124 extending downwardly
from and integrally with its periphery. The vertical wall section
124 is inserted in a gap 126 delimited between the vertical wall
112 of the upper member 106 and the vertical wall 116 of the lower
member 108, as shown in FIG. 6. The size of the gap 126 is
configured to be somewhat larger, than the thickness of the
vertical wall section 124 and clearances (plays) are ensured
between the vertical wall section 124 and each of the vertical
walls 112, 116 outside and inside it, thereby enabling the rubber
membrane 102 to displace up and down. Further the axial length
(height) of the vertical wall section 124 is configured so that its
lower end may not abut on the outer peripheral portion 118 of the
lower member 108.
[0065] The grid 110 of the upper member 106 and the grid 114 of the
lower member 108 have a same grid configuration. More particularly,
the grid 114 of the lower member assumes, as shown in FIGS. 9A and
9C, the same configuration as in the first example, and
accordingly, is constructed of a plurality of annular portions 114a
and joint portions 114b thereby delimiting a plurality of
through-holes 128. The grid 110 of the upper member 106 assuming
the same configuration as the grid 114 is provided with
through-holes 130 in the same configuration and arrangement as that
of the through-holes 128 of the lower member 108. Both the upper
member 106 and the lower member 108 constructed above are assembled
together, with respective through-holes 130, 128 situated mutually
in register.
[0066] The rubber membrane 102 is formed on its either surface
integrally with projecting streaks 132 that abut on respective
surfaces of the grids 110, 114 vis-a-vis either surface of the
rubber membrane and surround outer peripheries of the through-holes
130, 128, thus extending around full circumferences of them. The
configuration and the arrangement of the projecting streaks 132 is
the same as in the first example as shown in FIG. 9B, and
consequently, the projecting streaks 132 consist of a plurality of
annular projecting pieces 132a and radial projecting pieces
132b.
[0067] By the anti-vibration device thus constructed in the third
example, in addition to the effects achieved in the first example,
it is possible to prevent the generation of the impinging sound of
the rubber membrane 102 on the grids 110, 114 and noise, on account
of the fact that the vertical wall section 124 provided at the
periphery of the rubber membrane 102 precludes flapping of the
periphery of the rubber membrane 102 due to a sudden hydraulic
pressure change.
[0068] Further because of the provision of the vertical wall
section 124, the rubber membrane 102 is easy to identify between
its obverse side and reverse side. The rubber membrane 102 is
superior also in workability when inserting the rubber membrane 102
into the vacant space inside the upper member 106. At that time the
rubber membrane 102 is free from turning up at the peripheral part,
so that assembling property of the partition member 100 is
enhanced.
[0069] Otherwise with a view to positioning the rubber membrane 102
in the revolution direction, the lower end or tip of the vertical
wall section 124 may be provided with a cutout or a convex portion
so as to be fitted in a convex portion or a recess provided on the
vertical wall 112 or 116 of the upper member 106 or the lower
member 108. This can ensure the radial projecting pieces 132b
provided on the rubber membrane 102 to rest on the joint portions
of the grids 110, 114.
FOURTH EXAMPLE
[0070] FIGS. 10 to 12 indicate a fourth example of this invention.
The fourth example is different from the first example in
construction of the partition member dividing the fluid-sealed
chamber 26. The fourth example will be hereinafter described, but
the description on similar elements designated by like reference
numerals to the first example will be omitted unless otherwise
stated, since these are regarded as being of the same
construction.
[0071] In the fourth example, a partition 200 comparting the
fluid-sealed chamber 26 comprises a disk-like rubber membrane 202
as a valve member partitioning the first chamber 26a and the second
chamber 26b, an upper member (the first member) 204 disposed at the
vibration-insulating base 14 side relative to the rubber membrane
202, and a lower member (the second member) 206 disposed at the
diaphragm 22 side relative to the rubber membrane 202.
[0072] The upper member 204 is a molding product of resin (e.g.
polyphthalamide), and includes, as illustrated in FIG. 11, a
central shelf part (the first grid) 204a disposed vis-a-vis the
upside of the rubber membrane 202 and limiting its upward
displacement, and a peripheral part 204b having a groove 208 for
forming the orifice channel 28. The peripheral part 204b is of a
nearly cylindrical form and has, on its outer peripheral surface,
the groove 208 extending circumferentially in vertically two
cycles. Further the peripheral part 204b is defined with an opening
210 by being cut out partly from its upper wall, the opening 210
putting the orifice channel 28 and the first chamber 26a into
communication with each other.
[0073] The central shelf part 204a of the upper member 204 is
disposed to span the cylindrical peripheral part 204b in a manner
dividing its interior relative to an axially central plane up and
down, and accordingly, assumes a disk form. Although not
illustrated, the central shelf part 204a is configured in the same
grid form as in the first example, and has a plurality of
through-holes 212 defined by this grid. The underside of the
central shelf part 204a, namely the surface of it opposing the
rubber membrane 202 is formed with a depressed part 214 for
receiving therein the rubber membrane 202. Around the depressed
part 214, a flat opening edge 216 assuming a ring form is
ensured.
[0074] The lower member 206 is of a press molding product of metal
sheet, and is composed of a disk-form central shelf part (the
second grid) 206a disposed to oppose the underside of the rubber
membrane 202 and limiting its downward displacement and a
peripheral part 206b crimped and secured to the crimped area of the
cylindrical fitting 16 and the bottom fitting 18. Between the
central shelf part 206a and the peripheral part 206b, there is
formed an intermediate step part 206c constituting the orifice
channel 28 along with the peripheral part 204b of the upper member
204. By being crimped and secured at the peripheral part 206b, the
lower member 206 will press the top end of the peripheral part 204b
of the upper member 204 against a step portion 14b provided in the
peripheral area of the underside of the vibration-insulating base
14.
[0075] The central shelf part 206a of the lower member 206 is
provided to project upwardly from the intermediate step part 206c
and disposed inside the lower side of the peripheral part 204b so
as to oppose the central shelf part 204a of the upper member 204.
The central shelf part 206a of the lower member 206 constitutes a
flat plane element abutting on an edge surface 216 of an opening of
the depressed part 214 of the upper member 204 so as to shut the
opening of the depressed part 214, but has no depression for
housing the rubber membrane 202, as is the case with the upper
member 204. Instead, as shown in FIG. 11C, there is formed a
clearance 218 limiting displacements of the rubber membrane 202
between the upper member 204 and the lower member 206, by pressing
the central shelf part 206a of the lower member 206 onto the
opening edge surface 216 in the depressed part 214 of the upper
member 204 upon crimping and fixing stated above. The dimension L
of the clearance 218 here is defined only by the depth of the
depressed part 214.
[0076] As an aside, the central shelf part 206a of the lower member
206 is configured in a similar grid shape to that of the central
shelf part 204a of the upper member 204, and has a plurality of
through-holes 220 delimited by the grid. The intermediate step part
206c of the lower member 206 is provided with an opening 222
putting the orifice channel 28 and the second chamber 26b into
communication with each other.
[0077] The rubber membrane 202 is situated within the clearance
218, and its vertical displacements are limited between the upper
and lower central shelf parts 204a, 206a. The dimension L of the
clearance 218 is set to be somewhat larger than the thickness of
the rubber membrane 202, thereby enabling the rubber membrane 202
to displace up and down. On either surface of the rubber membrane
202 there are formed, as is the case with the first example,
projecting streaks 224 integral with the either surface that abut
on respective surfaces of the upper and lower central shelf parts
204a, 206a facing the either surface and surround the through-holes
212, 220 at their whole outer peripheries.
[0078] In the anti-vibration device of the fourth example thus
constructed, the size of the clearance 218 housing therein the
rubber membrane 202 is defined only by the depth of the depressed
part 214 provided in the upper member 204. Therefore for the lower
member 206 it is possible to ensure a rigidity withstanding the
crimping strength by making it of metal whereas for the upper
member 204 it is possible to ensure a dimensional precision of the
movable clearance 218 without applying cutting processing by making
it of resin.
[0079] With the fourth example of anti-vibration device, due the
fact that the dimension of the movable clearance of the rubber
membrane 202 is regulated only by the depth of the depressed part
214, both the upper and lower members 204, 206 are constructed so
as to abut only on the opening end surface 216 of the depressed
part 214 and the peripheral area of the central shelf part 206a,
but so as not to come into contact with each other in other
portions or areas than the above. Here, the positioning of the
upper member 204 and the lower member 206 is carried out, as
regards the radial direction, by the inner peripheral surface of
the cylindrical fitting 16 and as regards the height direction,
between the step portion 14b of the vibration-insulating base 14
and the crimped area.
[0080] As regards the revolution direction, its positioning can be
carried out by elongating the lower end of the vertical wall 226 at
the peripheral part 204b of the upper member 204 as shown in FIG.
12. The vertical wall 226 shuts off the flow in the circumferential
direction at the lower end of the orifice channel 28 thereby
serving to induce the fluid to the opening 222 of the lower member
206. The lower end of the vertical wall 226 is elongated downwardly
of the underside of the peripheral portion 204b as an elongated
portion 228, which is inserted into the opening 222 of the lower
member 206 to abut on the one opening edge, whereby it is possible
to peroform the positioning of the upper member 204 and the lower
member 206 in the revolution direction and simultaneously ensure an
open area of the opening 222.
[0081] Further because of the fact that the upper member 204 and
the lower member 206 are brought into abutment only at the butt
joining part between the opening end surface 216 of the depressed
part 214 and the peripheral portion of the central shelf part 206a,
as shown in FIG. 11B, there is ensured a clearance between the
lower end of the peripheral part 204b of the upper member 204 and
the intermediate step part 206c of the lower member 206. Due to
this clearance it is conceivable that the fluid flowing through the
orifice channel 28 can leak without being shut off completely by
the vertical wall 226. However, because the lower end of the
vertical wall 226 is elongated as described above, such leak can be
avoided.
[0082] In addition, as shown in FIG. 12C, the elongated portion 228
of the vertical wall 226 may be provided with a hook 230, which can
be caught in the opening edge of the opening 222 of the lower
member 206. By this expedient, it is possible to prevent possible
revolution and disengagement of the upper member 204 and the lower
member 206 upon fabrication.
FIFTH EXAMPLE
[0083] FIGS. 13 and 14 indicate a fifth example of this invention.
In the fifth example, for the upper member 204 a resin is adopted
likewise as in the fourth example, but for the lower member 206 an
aluminum casting product is adopted, instead of the press steel
sheet.
[0084] Moreover in the fifth example, the lower member 206 as well
as the upper member 204 are provided at their peripheral areas with
grooves 203b constituting the orifice channels 28. More
particularly, the upper member 204 includes the central shelf part
204a and the peripheral part 204b having a groove 208a constituting
an upper channel 28a of the vertical two-cycle orifice channel 28.
On the other hand, the lower member 206 includes the central shelf
part 206a, and the peripheral part 206b having a groove 208b
constituting a lower channel 28b, wherein the upper wall of the
peripheral part 206b assuming a U-form in section forms the upper
channel 28a together with the peripheral part 204b of the upper
member 204 whereas the lower wall of it is elongated outwards to be
crimped and secured to the crimped area of the second attachment
member 12.
[0085] Also in this fifth example the central shelf part 206a of
the upper member 204 is provided with the depressed part 214,
against which the flat central shelf part 206a of the lower member
106 is butted so as to obstruct the opening of the depressed part
214 whereby the clearance 218 limiting displacements of the rubber
membrane 202 is formed between the upper member 204 and the lower
member 206 and the size of the clearance 218 is defined only by the
depth of the depressed part 214.
[0086] Here, for positioning purposes in the revolution direction
of the upper member 204 and the lower member 206, the lower end of
a vertical wall 232 provided on the upper member 204 is elongated
as shown in FIG. 14. This vertical wall 232 is to induce the fluid
from the upper channel 28a to the lower channel 28b. By elongating
the vertical wall 232 in this way and inserting its elongated
portion 234 into an opening 236 for positioning provided in the
peripheral part 206b of the lower member 206, the upper member 204
and the lower member 206 are subjected to positioning in the
revolution direction. Due to the positioning, leak of fluid in the
clearance between the vertical wall 232 and the peripheral portion
206b of the lower member 206 is also prevented.
[0087] According to the fifth example, in addition to the effects
obtained in the fourth example, a high degree of design freedom is
obtainable because both the upper member 204 and the lower member
206 are of one molding product.
* * * * *